The primary goal of this project is an understanding of collagen structure from the molecular to the fibril level. Emphasis has been on conventional and scanning transmission electron microscopy and analysis of micrographs by computer methods. During the current year research has shifted to fitting of models to x-ray diffraction data based on a new model, if compressed to place collagen molecules in cross sections on a near-hexagonal lattice, fits positional and intensity data obtained by x-ray diffraction of rat tail tendon collagen fibers.